Apparatus for driving lens in camera

ABSTRACT

An apparatus for driving a lens in a camera includes a lens module installed in a reciprocating and sliding manner in an inside of a lens barrel, a lead screw installed on the lens barrel, for being rotated by a driving motor, and a power transferring member assembled on the lens module and equipped with a tooth-shaped part that corresponds to a tooth shape of the lead screw. The lens module has a lens and a slider having a mounting unit for mounting the lens and receiving the power transferring member in a movable manner. The mounting unit has a through groove in which one end of the power transferring member is fit and supported and a slit groove in which the other end of the power transferring member is fit to be supported for being movable in a direction perpendicular to the movement direction of the slider.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.2003-35764 filed Jun. 3, 2003 in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference inits entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for driving a lens in acamera.

2. Description of the Related Art

Generally, a video camera, a digital still camera, a monitoring camerahave an optical apparatus for taking a photograph of an image. Amongthem, a lens module for performing functions of focusing and/or zoominga target image is installed in a movable manner on a lens barrel. Thelens module is reciprocated in the inside of the lens barrel by apredetermined driving force.

For such reciprocating motion, a guide shaft is installed within thelens barrel, and a slider equipped with a zoom lens and/or a focusinglens is installed in a sliding manner on the guide shaft. In addition, adriving motor and a lead screw for reciprocating the slider areinstalled on the lens barrel. The slider has a power transferring memberhaving a tooth-shaped part for joining to a screw thread of the leadscrew on it. The power transferring member is assembled to the slider bya separate part and connected to the lead screw.

However, recently, as light-weight and compact-sizing trends arepursued, the lens barrel, the driving motor and the lead screw aregetting smaller in their sizes as well as the lens module. Particularly,as the trend of pursuing accuracy and low power consumption develops forthe driving motor and the lead screw, high part accuracy is required.Therefore, if there is an assembling error of the lead screw withrespect to the lens barrel, or an assembling error of the powertransferring member, connection of the lead screw and the powertransferring member may not be smoothly performed. In that case, thetooth-shaped part of the power transferring member may deviate beyondthe allowable error range with respect to the axial direction of thelead screw. Accordingly, a big load is applied on the driving motor andbig frictional force is applied on the lead screw, so that excessivenoise may be generated or normal operation may not be performed.

SUMMARY OF THE INVENTION

The above disadvantages are overcome and other advantages are realizedby embodiments of the present invention. Embodiments of the presentinvention comprise a lens module slidably installed in a lens barrel anda lead screw rotatably installed in the lens barrel. The lead screw ispreferably rotated by a driving motor. A power transferring member isassembled on the lens module. The power transferring member comprises atooth shaped part corresponding to the lead screw. The lens modulecomprises a mounting unit adapted to movably receive the powertransferring unit. The mounting unit preferably comprises a throughgroove adapted to receive a first end of the power transferring member,which is preferably conical in shape. The mounting unit furtherpreferably comprises a slit groove adapted to receive a second end ofthe power transferring member. The slit groove preferably has a firstslit part having a small width and a second slit part having a largerwidth. The second end of the power transferring member preferably has across section having a first width corresponding to the width of thefirst slit part and a second width corresponding to the width of thesecond slit part. The power transferring member is preferably rotatablyabout a longitudinal axis such that the second end is movable throughthe first slit part in a first orientation, but not movable through thefirst slit part in a second orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and other advantages of the present invention will bemore apparent from the following detailed description when taken inconjunction with the accompanying drawing figures, in which:

FIG. 1 is a separated, perspective view showing an apparatus for drivinga lens in a camera according to an embodiment of the present invention;

FIG. 2 is a side view showing an extract of a portion of FIG. 1;

FIG. 3 is a front view of the portion illustrated in FIG. 2;

FIG. 4 is a separated, perspective view showing an extract of a portionof FIG. 1;

FIG. 5 is a front view showing a power transferring member mounted on aslider according to an embodiment of the invention;

FIG. 6A is a drawing showing a portion of FIG. 5; and

FIG. 6B is a drawing schematically showing a second axis rotated 90degree from of the portion illustrated in FIG. 6A.

It will be understood that in the drawings, like reference numeralsrefer to like features and structures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will bedescribed in detail with reference to the accompanying drawing figures.

The matters defined in the description such as a detailed constructionand elements are provided to assist in a comprehensive understanding ofthe invention. Thus, it should be understood that the descriptioncontained herein is intended to be exemplary, and is not intended toinclude every possible embodiment of the present invention. Also,well-known functions or constructions are not described in detail inorder to focus on the novel aspects of the herein described embodiments.

Referring to FIG. 1, an apparatus for driving a lens in a cameraaccording to an embodiment of the present invention includes a lensmodule 20 installed in a sliding manner in an inside of a lens barrel10, a lead screw 30 installed on the lens barrel 10, and adapted to berotated by a driving motor 11, and a power transferring member 40assembled with the lens module 20, connected to the lead screw 30 byteeth adapted to engage the threads of the lead screw 30.

The lens barrel 10 is installed within a main body of a camera (notshown). In the inside of the lens barrel 10, a focusing lens forfocusing a target image to be photographed and a zoom lens are installedin a movable manner. Also, at the end of the barrel 10 in aphotographing direction of the lens barrel 10, a group of lensesincluding an object lens 12 is joined to a barrel cover 13. In theinside of the lens barrel 10 a guide shaft 15 for guiding movement ofthe lens module 20 is installed. In the presently described embodiment,the guide shaft 15 is fit into the inside of the lens barrel 10 and isalso joined to the barrel cover 13.

Referring to FIG. 2 and FIG. 3, the lens module 20 includes the focusinglens or the zoom lens and is installed movably within the lens barrel10. In the present embodiment, the lens module 20 has a slider 21supported in a sliding manner on the guide shaft 15 and a zoom lens 23supported by the slider 21. The slider 21 has a mounting unit 21 a forsupporting the power transferring member 40 in a movable manner. Themounting unit 21 a will be described in further detail below.

The lead screw 30 is rotatably supported by a supporting bracket 31joined to the lens barrel 10, and has a screw thread on its outerperiphery. On the supporting bracket 31, a driving motor 11 issupported. The lead screw 30 is exposed to the inside of the lens barrel10 and arranged in parallel with the guide shaft 15. Thus, the slider 21is able to move along the direction of the lead screw 30 and the guideshaft 15.

While being assembled to the slider 21, the power transferring member 40is joined to the lead screw 30 in a tooth combining manner. Therefore,upon rotation of the lead screw 30, the power transferring member 40 ismoved to the axial direction of the lead screw 30 along the lead screw30, and finally the slider 21 can be moved. Referring to FIG. 4, suchpower transferring member 40 has a tooth-shaped part 41 into which thelead screw 30 is fit and joined in a tooth combining manner. The powertransferring member 40 further has a first axis 43 of a conicalcross-section on its one end, and a second axis 45 of a non-circularcross section on its other end.

The tooth-shaped part 41 preferably has a U-shape whose upper part isopen, and a rib 41 a adapted to be joined to the lead screw 30 in atooth combining manner formed in the inside of the U-shape. The leadscrew 30 is fit in and connected with the power transferring member 40through the upper open part of the tooth-shaped part 41. The first axis43 is of a conical shape which is tapered in its one end. The secondaxis 45 is of a non-circular cross section. Preferably, the second axis45 has a cross section having short width and long width whose widthsare different from each other.

The power transferring member 40 having the foregoing construction isassembled to the mounting unit 21 a of the slider 21 in a movablemanner. For that purpose, the mounting unit 21 a has a through groove 24for receiving and supporting the first axis 43 and a slit groove 25 forreceiving and supporting the second axis 45. The first axis 43 fit intothe through groove 24 allows for moving up, down, right and left due tothe conical shape. The power transferring member 40 is connected to thelead screw 30 after having been rotated at or about 90 degrees after fitinto the through groove 24 and the slit groove 25 in the first direction“A.” FIG. 5 shows the power transferring member 40 having been fit inthe first direction “A.” FIG. 3 shows the power transferring member 40after it has been rotated 90 degrees after being fit in the firstdirection “A.”

Referring to FIG. 6A, the slit groove 25 is divided into a first slitpart 25 a and a second slit part 25 b. The first slit part 25 a isformed for being opened in the first direction “A” and has a width W1that corresponds to the short width w1 of the second axis 45 withrespect to the second direction “B” perpendicular to the first direction“A.” As the second axis 45 is joined by passing through the first slitpart 25 a through the short width w1, the short width w1 is formedsmaller than the width W1 of the first slit part 25 a.

The second slit part 25 b is connected with the first slit part 25 a andextended further to the first direction “A.” Such second slit part 25 b,as shown in FIG. 6B, has a first width W2 that corresponds to the longwidth w2 of the second axis 45. Preferably, the first width W2 of thesecond slit part 25 b is formed larger than the long width w2. Also, thesecond slit part 25 b is formed to have a second width W3 that isnaturally larger than the short width w1 in the first direction “A.”Therefore, if the second axis 45 is rotated at or about 90 degrees afterbeing fit into the second slit part 25 b in the first direction “A”through the first slit part 25 a, the long width w2 of the second axis45 becomes perpendicular to the first slit part 25 a, as shown in FIG.6B, so that the second axis 45 can not be moved through the first slitpart 25 a. Also, the second axis 45 preferably has a degree of freedomat the second slit part 25 b, of being movable a predetermined distancein the first direction “A.” Namely, as the short width w1 of the secondaxis 45 is smaller than the second width W3 of the second slit part 25 bin the first direction “A,” the second axis 45 could be moved apredetermined distance in the first direction “A” as shown in dashedlines in FIG. 6B. Therefore, the second axis 45 of the powertransferring member 40 is able to be position-adjusted with respect tothe first direction “A.” As a result, the position of the powertransferring member 40 can be adjusted.

Upon assembling of the power transferring member 40 to the mounting unit21 a, a spring 50 is additionally provided. The spring 50 fits into thesecond axis 45, and applies pressure on the power transferring unit 40toward the side of the through groove 24. Therefore, the first axis 43has a degree of freedom with respect to external force while remainingfit in the through groove 24.

In an apparatus for driving a lens having the foregoing construction,the power transferring member 40 can be assembled to flexibly cope withassembly or manufacturing error of the lead screw 30. More specifically,the power transferring member 40 at its height, can deliver power withina predetermined distance in the up and down directions with the leadscrew 30 fit in its U-shaped groove by the U-shaped structure of thetooth-shaped part 41.

Also, the first axis 43 is formed in a conical shape. Thus, fineadjustment for a constant height or twisted angel is possible in theevent that the first axis 43 is pushed back by a load of an assemblyerror.

Also, the second axis 25 is able to be fine-adjusted in the firstdirection “A” at the second slit part 25 b. Thus, in case the lead screw30 and the power transferring member 40 are assembled in a non-parallelstate with respect to each other, the second axis 25 has a degree offreedom to sufficiently compensate for the non-parallel state.

As is apparent from the foregoing, according to an embodiment of thepresent invention for driving a lens in a camera, the power transferringmember for connecting the lens module to the lead screw has a degree offreedom by which fine position change is possible with respect to manydirections.

Advantageously, a frictional load generated between the powertransferring member and the lead screw due to assembly and manufacturingerrors of the lead screw can be reduced. Power consumption of thedriving motor can be minimized and noise due to friction can also bereduced.

While the invention has been shown and described with reference tocertain preferred embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

1. An apparatus for driving a lens in a camera comprising: a lens moduleslidably installed in a lens barrel; a lead screw rotatably installed inthe lens barrel; a power transferring member assembled on the lensmodule, wherein said power transferring member comprises a tooth shapedpart corresponding to a shape of said lead screw, and wherein said lensmodule comprises a mounting unit adapted to movably receive the powertransferring member, said power transferring member having a firstorientation in which said power transferring member is removable fromsaid mounting unit and a second orientation in which said powertransferring member is not removable from said mounting unit.
 2. Theapparatus of claim 1, further comprising a driving motor, wherein saidlead screw is adapted to be rotated by the driving motor.
 3. Theapparatus of claim 1, wherein the mounting unit comprises a throughgroove adapted to receive a first end of the power transferring member.4. The apparatus of claim 3, wherein said first end of the powertransferring member is conical.
 5. The apparatus of claim 1, wherein themounting unit comprises a slit groove adapted to receive a second end ofthe power transferring member.
 6. The apparatus of claim 5, wherein saidsecond end of the power transferring member is movable in a directionperpendicular to a sliding direction of the lens module.
 7. Theapparatus of claim 5, wherein said slit groove has a first slit part anda second slit part, the first slit part having a width smaller than awidth of the second slit part.
 8. The apparatus of claim 7, wherein saidsecond end of the power transferring member has a cross section having afirst width corresponding to the width of the first slit part, and asecond width corresponding to the width of the second slit part.
 9. Theapparatus of claim 8, wherein said power transferring member isrotatable about a longitudinal axis such that in the first orientationsaid second end is movable through said first slit part, and in thesecond orientation said second end is not movable through said firstslit part.
 10. The apparatus of claim 1, wherein said mounting unit isintegrally formed with a slider connected to the lens module.
 11. Theapparatus of claim 1, wherein an object lens and a barrel cover aredisposed at one end of the lens barrel.